The word(s) "heart" appears 169 time(s) in 159 verse(s) in Quran in Muhammad Pickthal translation.

(131) Will they then not meditate on the Qur'an, or are there locks on the hearts?

(132) Or do those in whose hearts is a disease deem that Allah will not bring to light their (secret) hates?

(133) He it is Who sent down peace of reassurance into the hearts of the believers that they might add faith unto their faith. Allah's are the hosts of the heavens and the earth, and Allah is ever Knower, Wise -

(134) Those of the wandering Arabs who were left behind will tell thee: Our possessions and our households occupied us, so ask forgiveness for us! They speak with their tongues that which is not in their hearts. Say: Who can avail you aught against Allah, if He intend you hurt or intend you profit? Nay, but Allah is ever Aware of what ye do.

(135) Nay, but ye deemed that the messenger and the believers would never return to their own folk, and that was made fairseeming in your hearts, and ye did think an evil thought, and ye were worthless folk.

(136) Allah was well pleased with the believers when they swore allegiance unto thee beneath the tree, and He knew what was in their hearts, and He sent down peace of reassurance on them, and hath rewarded them with a near victory;

(137) When those who disbelieve had set up in their hearts zealotry, the zealotry of the Age of Ignorance, then Allah sent down His peace of reassurance upon His messenger and upon the believers and imposed on them the word of self-restraint, for they were worthy of it and meet for it. And Allah is Aware of all things.

(138) Lo! they who subdue their voices in the presence of the messenger of Allah, those are they whose hearts Allah hath proven unto righteousness. Theirs will be forgiveness and immense reward.

(139) And know that the messenger of Allah is among you. If he were to obey you in much of the government, ye would surely be in trouble; but Allah hath endeared the faith to you and hath beautified it in your hearts, and hath made disbelief and lewdness and rebellion hateful unto you. Such are they who are the rightly guided.

(140) The wandering Arabs say: We believe. Say (unto them, O Muhammad): Ye believe not, but rather say "We submit," for the faith hath not yet entered into your hearts. Yet, if ye obey Allah and His messenger, He will not withhold from you aught of (the reward of) your deeds. Lo! Allah is Forgiving, Merciful.